Hydroxyl radical reactions and the radical scavenging activity of β-carboline alkaloids

Discovery and identification of natural alkaloids with potential to impact insulin resistance syndrome in Cyclocarya paliurus. (Batal) leaves by UPLC-QTOF-MS combined with HepG2 cells

Cyclocarya paliurus (Batal.) leaves, which contain a range of bioactive compounds, have been used as a traditional Chinese medicine homologous food since ancient times. However, there is a paucity of literature on comprehensive studies of alkaloids in the leaves of Cyclocarya paliurus (Batal.). For the first time, this study aimed to discover and identify alkaloids extracted from Cyclocarya paliurus (Batal.) leaves by ultra-high performance liquid chromatography-quadrupole-time-of-flight tandem mass spectrometry (UPLC-QTOF-MS). A total of ten alkaloids have been identified from Cyclocarya paliurus (Batal.) leaves based on accurate mass spectra (mass accuracy, isotopic spacing and distribution) and comparison to fragmentation spectra reported in the literature. In vitro, alkaloids alleviated insulin resistance by increasing glucose consumption and glycogen content in insulin resistance HepG2 cells. The RNA-seq and western blotting results showed that alkaloids could upregulate the expression of phosphatidylinositol 3-kinase (PI3K), and increase the phosphorylation of insulin receptor protein kinase B (AKT). This study not only clarified the chemical constituents and revealed that diverse alkaloids also presented from Cyclocarya paliurus (Batal.) leaves, also, it will provide chemical information on potential compounds for developing new drugs.

Research progress on the role of reactive oxygen species in the initiation, development and treatment of breast cancer

According to international cancer data, breast cancer (BC) is the leading type of cancer in women. Although significant progress has been made in treating BC, metastasis and drug resistance continue to be the primary causes of mortality for many patients. Reactive oxygen species (ROS) play a dual role in vivo: normal levels can maintain the body's normal physiological function; however, high levels of ROS below the toxicity threshold can lead to mtDNA damage, activation of proto-oncogenes, and inhibition of tumor suppressor genes, which are important causes of BC. Differences in the production and regulation of ROS in different BC subtypes have important implications for the development and treatment of BC. ROS can also serve as an important intracellular signal transduction factor by affecting the antioxidant system, activating MAPK and PI3K/AKT, and other signal pathways to regulate cell cycle and change the relationship between cells and the activity of metalloproteinases, which significantly impacts the metastasis of BC. Hypoxia in the BC microenvironment increases ROS production levels, thereby inducing the expression of hypoxia inducible factor-1α (HIF-1α) and forming "ROS- HIF-1α-ROS" cycle that exacerbates BC development. Many anti-BC therapies generate sufficient toxic ROS to promote cancer cell apoptosis, but because the basal level of ROS in BC cells exceeds that of normal cells, this leads to up-regulation of the antioxidant system, drug efflux, and apoptosis inhibition, rendering BC cells resistant to the drug. ROS crosstalks with tumor vessels and stromal cells in the microenvironment, increasing invasiveness and drug resistance in BC.

Formation, Identification, and Occurrence of the Furan-Containing β-Carboline Flazin Derived from l-Tryptophan and Carbohydrates

β-Carbolines (βCs) are bioactive indole alkaloids found in foods and in vivo. This work describes the identification, formation, and occurrence in foods of the βC with a furan moiety flazin (1-[5-(hydroxymethyl)furan-2-yl]-9H-pyrido[3,4-b]indole-3-carboxylic acid). Flazin was formed by the reaction of l-tryptophan with 3-deoxyglucosone but not with 5-hydroxymethylfurfural. Its formation was favored in acidic conditions and heating (70-110 °C). The proposed mechanism of formation occurs through the formation of intermediates 3,4-dihydro-β-carboline-3-carboxylic acid (imines), followed by the oxidation to C═O in the carbohydrate chain and aromatization to βC ring with subsequent dehydration steps and cyclization to afford the furan moiety. Flazin is generated in the reactions of tryptophan with carbohydrates. Its formation from fructose was higher than from glucose, whereas sucrose gave flazin under acidic conditions and heating owing to hydrolysis. Flazin was identified in foods by HPLC-MS, and its content was determined by HPLC-fluorescence. It occurred in numerous processed foods, such as tomato products, including crushed tomato puree, fried tomato, ketchup, tomato juices, and jams, but also in soy sauce, beer, balsamic vinegar, fruit juices, dried fruits, fried onions, and honey. Their concentrations ranged from not detected to 22.3 μg/mL, with the highest mean levels found in tomato concentrate (13.9 μg/g) and soy sauce (9.4 μg/mL). Flazin was formed during the heating process, as shown in fresh tomato juice and crushed tomatoes. These results indicate that flazin is widely present in foods and is daily uptaken in the diet.

Nutritional and functional insight into novel probiotic lycopene-soy milk by genome edited Bacillus subtilis

Nutritional and functional soy-based milk gains growing attention globally in food industry. However, its poor sensorial attributes, single flavor, and limited substance variety become critical issues in displaying balanced nutrition and multifunction for health. Herein, a novel probiotic lycopene-soy milk was developed by genome edited Bacillus subtilis harboring lycopene biosynthesis cassette with efficient lycopene production of 25.73 ± 1.57 mg/g DCW. Further investigation displayed desirable pH, reducing sugar, protein, total phenolic content and isoflavone for achieved milk than conventional soy milk, implying it with well-balanced nutritional quality. Notably, achieved milk exhibited stronger antioxidant capacity and higher isoflavone bioavailability for functionality. Moreover, it possessed significantly high scores for taste, appearance, and overall acceptability, suggesting its excellent sensorial attributes. To our delight, it is the first time to fortify soy-milk with probiotic and lycopene by genome edited B. subtilis to explore additive effect on improving nutritional value and functionality for food application.

Synthesis and diverse biological activities of substituted indole β-carbolines: a review

β-Carboline bearing indole is one of the heterocyclic compounds that play a vital role in medicinal chemistry with various pharmacological effects such as anticancer, anti-acetylcholinesterase, anti-inflammation, antimalarial, antibacterial, anti-diabetic, and antioxidant. Over the last two decades, many studies on the synthesis and biological activity of indole β-carboline compounds have been conducted yet there is no appropriate data summary has been presented. Thus, the goal of this review was to highlight the synthesis pathway and bioactivity of substituted indole β-carboline reported from 2005 to date. In addition, this will encourage further investigation into the synthesis and evaluation of new indole β-carboline, in the hope of contributing to the development of potentially new medications for the treatment of various ailments.

Identification, Formation, and Occurrence of Perlolyrine: A β-Carboline Alkaloid with a Furan Moiety in Foods

β-Carbolines are naturally occurring bioactive alkaloids found in foods and in vivo. This research reports the identification, characterization, mechanism of formation, and occurrence of perlolyrine (1-(5-(hydroxymethyl)furan-2-yl)-9H-pyrido[3,4-b]indole), a β-carboline with a furan moiety. Perlolyrine did not arise from l-tryptophan and hydroxymethylfurfural but from the reaction of l-tryptophan with 3-deoxyglucosone, an intermediate of carbohydrate degradation. The mechanism of formation occurs through 3,4-dihydro-β-carboline-3-carboxylic acid intermediates (imines), followed by the oxidation of C1'-OH to ketoimine and oxidative decarboxylation at C-3, along with dehydration and cyclization to afford the β-carboline with a furan moiety. The formation of perlolyrine was favored in acidic conditions and temperatures in the range of 70-110 °C. Perlolyrine occurred in the reactions of tryptophan with carbohydrates. The formation rate from fructose was much higher than from glucose. Sucrose also gave perlolyrine under acidic conditions and heating. Perlolyrine was identified in many foods by HPLC-MS and analyzed by HPLC-fluorescence. It occurred in many processed foods such as tomato products including tomato puree, fried tomato, ketchups, tomato juices, and jams but also in soy sauce, beer, balsamic vinegar, fruit juices, dried fruits, fried onion, and honey. The concentrations ranged from an undetected amount to 3.5 μg/g with the highest average levels found in tomato concentrate (1.9 μg/g) and soy sauce (1.5 μg/mL). The results show that perlolyrine formed during the heating process of foods. It is concluded that perlolyrine is widely present in foods and it is daily ingested in the diet.

In vitro antioxidant activity evaluation of pine nut peptides (Pinus koraiensis) fermented by Bacillus subtilis LS-45

In this study, we utilized the remarkable capabilities of Bacillus subtilis ls-45 during the fermentation process to generate pine nut peptide. Through gene sequencing, we confirmed the proficiency of Bacillus subtilis ls-45 in producing protease, thereby serving as a valuable enzymatic source for protein hydrolysis. Our investigation focused on examining the variations in amino acid types and quantities between enzymatic pine nut protein peptide (EPP) and fermented pine nut protein polypeptide (FPP). Furthermore, we conducted a comprehensive assessment of the in vitro antioxidant activities of EPP and FPP, encompassing measurements of their Hydroxyl radical scavenging rate, Total reducing capacity, Superoxide anion scavenging rate, and ABTS+ radical scavenging rate. Notably, FPP exhibited superior antioxidant capacity compared to EPP. By employing semi-inhibitory mass concentration (IC50) analysis, we determined that FPP displayed enhanced efficacy in neutralizing hazardous free radicals when compared to EPP.

Exploring Natural Products as Radioprotective Agents for Cancer Therapy: Mechanisms, Challenges, and Opportunities

Radiotherapy is an important cancer treatment. However, in addition to killing tumor cells, radiotherapy causes damage to the surrounding cells and is toxic to normal tissues. Therefore, an effective radioprotective agent that prevents the deleterious effects of ionizing radiation is required. Numerous synthetic substances have been shown to have clear radioprotective effects. However, most of these have not been translated for use in clinical applications due to their high toxicity and side effects. Many medicinal plants have been shown to exhibit various biological activities, including antioxidant, anti-inflammatory, and anticancer activities. In recent years, new agents obtained from natural products have been investigated by radioprotection researchers, due to their abundance of sources, high efficiency, and low toxicity. In this review, we summarize the mechanisms underlying the radioprotective effects of natural products, including ROS scavenging, promotion of DNA damage repair, anti-inflammatory effects, and the inhibition of cell death signaling pathways. In addition, we systematically review natural products with radioprotective properties, including polyphenols, polysaccharides, alkaloids, and saponins. Specifically, we discuss the polyphenols apigenin, genistein, epigallocatechin gallate, quercetin, resveratrol, and curcumin; the polysaccharides astragalus, schisandra, and Hohenbuehelia serotina; the saponins ginsenosides and acanthopanax senticosus; and the alkaloids matrine, ligustrazine, and β-carboline. However, further optimization through structural modification, improved extraction and purification methods, and clinical trials are needed before clinical translation. With a deeper understanding of the radioprotective mechanisms involved and the development of high-throughput screening methods, natural products could become promising novel radioprotective agents.

Antioxidant hepatic lipid metabolism can be promoted by orally administered inorganic nanoparticles

Accumulation of inorganic nanoparticles in living organisms can cause an increase in cellular reactive oxygen species (ROS) in a dose-dependent manner. Low doses of nanoparticles have shown possibilities to induce moderate ROS increases and lead to adaptive responses of biological systems, but beneficial effects of such responses on metabolic health remain elusive. Here, we report that repeated oral administrations of various inorganic nanoparticles, including TiO₂, Au, and NaYF₄ nanoparticles at low doses, can promote lipid degradation and alleviate steatosis in the liver of male mice. We show that low-level uptake of nanoparticles evokes an unusual antioxidant response in hepatocytes by promoting Ces2h expression and consequently enhancing ester hydrolysis. This process can be implemented to treat specific hepatic metabolic disorders, such as fatty liver in both genetic and high-fat-diet obese mice without causing observed adverse effects. Our results demonstrate that low-dose nanoparticle administration may serve as a promising treatment for metabolic regulation.

Development of a novel functional yogurt rich in lycopene by Bacillus subtilis

Functional lycopene-rich yogurt displays attractive nutritious and health-promoting benefits among existing functional dairy products, owing to supplement with lycopene which could enhance immunity, prevent cancer, and cardiovascular diseases. Due to poor stability and fat-solubility of lycopene, its incorporation into yogurt is challengeable. In this study, carotenoid genes for lycopene synthesis were co-introduced into probiotic Bacillus subtilis for efficient lycopene production. Further engineered B. subtilis was applied as adjunct starter culture for achieving lycopene-rich yogurt. Developed yogurt exhibited desirable physiochemical characteristics compared with plain yogurt. Moreover, lycopene-rich yogurt was endowed with significantly high antioxidant capacity. More importantly, this functionalized yogurt had attractive sensorial attributes for quality-assured food to facilitate consumer acceptance. As the first report of fortifying yogurt of lycopene using B. subtilis with improved functional properties, this study offers a new and facile clue to enrich bioactive lycopene and probiotic B. subtilis in yogurt for healthy and nutritional food development.

Evaluation of free radical quenching, anti-inflammatory activity together with anticancer potential of Lychnis coronaria and characterization of novel molecules from its extract through high resolution-liquid chromatography mass spectrometry coupled to structural biochemistry approach

Lychnis coronaria, a perennial (herbaceous) belonging to Caryophyllaceae has been traditionally used for treating different complications. However, the free radical scavenging effect, anti-inflammatory activity and anticancer property of methanolic extract of this plant has not been addressed. Most importantly, the chemical constituents present in the extract of Lychnis coronaria responsible for its diverse activities have not been scrutinized till date. Here, we used a complex approach for exploring the above mentioned effects of Lychnis coronaria. We performed rigorous phytochemical screening followed by quantification of tannins, phenols, alkaloids, quinones and sterols from the extract. Moreover we employed in vitro DPPH, ABTS , FRAP assay, albumin denaturation inhibition experiment, MTT assay, high resolution liquid chromatography mass spectrometry for measurng the reactive oxygen species quenching, anti-inflammatory and anticancer strength of Lychnis coronaria and for identifying the possible bioactive molecules. We identified two novel molecules panaxynol (polyacetylenic alcohol) and norharman (9H-Pyrido [3, 4-B] indole) following rigorous analysis of the extract. Following this, the binding affinity of these molecules was estimated using human cyclooxygenase (COX)-2 enzyme as target. Among the constituents of Lychnis coronaria norharman manifested stronger binding towards COX-2 compared to panaxynol. Most importantly, norharman showed high stability in the groove of COX2 as confirmed by molecular dynamics simulation. Collectively, Lychnis coronaria manifested free radical neutralizing, inflammation soothing and anticancer effect in concentration dependent manner and thus may serve as a promising phytotherapeutic in future.Communicated by Ramaswamy H. Sarma.

Application of High-Performance Liquid Chromatography with Fluorescence Detection for Non-Polar Heterocyclic Aromatic Amines and Acridine Derivatives Determination in Pork Loin Roasted in a Roasting Bag

Heat treatment of meat can lead to the formation of carcinogenic organic compounds. The influence of dried fruits on the formation of non-polar heterocyclic aromatic amines (carbolines) and nitrogen derivatives of polycyclic aromatic hydrocarbons (azaarenes) in roasted pork loin was elucidated. Two hundred grams of fruit per 1 kg of meat were used as stuffing. Carbolines, derivatives of pyridoimidazole and pyridoindole, and azaarenes (benzoacridines and dibenzoacridines) were determined by means of high-performance liquid chromatography with fluorescence detection. The total concentration of six δ-, γ- and α-carbolines in roasted pork loin was 1.3 ng/g. This content decreased by 64%, 58%, and 54% in pork loin stuffed with prunes, apricots, and cranberries, respectively. Concentrations of β-carbolines (harmane and norharmane) increased under the influence of added fruits. The norharmane content increased the most, from 2.2 ng/g in the control sample to 12.3 ng/g in meat prepared with cranberries. The harmane content increased from 1.0 ng/g to 3.6 ng/g in meat with prunes. The total concentration of azaarenes (two benzoacridines and dibenzo[a,c]acridine), which was close to 0.1 ng/g, decreased in dishes with prunes and apricots by 54% and 12%, respectively. Azaarenes were not found in samples of meat stuffed with cranberries.

Formation, Characterization, and Occurrence of β-Carboline Alkaloids Derived from α-Dicarbonyl Compounds and l-Tryptophan

β-Carbolines (βCs) are naturally occurring bioactive alkaloids, whereas α-dicarbonyl compounds are reactive substances generated in foods and in vivo. In this work, l-tryptophan reacted with α-dicarbonyl compounds affording new β-carbolines. Glyoxal afforded 1-hydroxymethyl-β-carboline (HME-βC) and its 3-carboxylic acid, and methylglyoxal afforded 1-(1-hydroxyethyl)-β-carboline (HET-βC) and its 3-carboxylic acid. 3-Deoxyglucosone afforded 1-(1,3,4,5-tetrahydroxypent-1-yl)-β-carboline isomers (1a/b), 1-(1,4,5-trihydroxypent-1-yl)-β-carboline (2), and 1-(1,5-dihydroxypent-3-en-1-yl)-β-carboline (3). The formation of these βCs increased under acidic conditions and with increasing temperature. A mechanism is proposed explaining the conversion of a carbonyl into a hydroxy group based on tautomerism and cyclization to the dihydro-βC-3-COOH intermediates, which were isolated and gave the βCs. These α-dicarbonyl-derived βCs occurred in model reactions of l-tryptophan with fructose or glucose incubated under heating and can be considered as advanced glycation end products (AGEs). They were also present in foods and formed during heating processes. HET-βC appeared in processed foods, reaching up to 309 ng/g, with the highest amount found in dried tomato, fried onion, toasted bread, and Manuka honey. HME-βC was only detected in some foods with lower amounts than HET-βC. HET-βC appeared in foods as a racemic mixture of enantiomers suggesting the same mechanism of formation as the synthetized product. α-Dicarbonyl-derived βCs (HET-βC, HME-βC, and 1a/b-3) occur in foods and food processing and, therefore, they are ingested during diet.

Process optimization and antioxidative activity of polyphenols derived from different seaweed species Sargassum Miyabei, Undaria Pinnatifida Suringar, and Sargassum Thunbergii

The aim of this study was to extract the polyphenols from three major seaweed species such as Sargassum miyabei, Undaria pinnatifida suringar, and Sargassum thunbergii, which are found in the coastal province (Guangdong), a longest coastal line in China. It was found that the Sargassum thunbergii produced more polyphenols (34.99 mg) as compared to Sargassum miyabei (23.26 mg) and Undaria pinnatifida suringar (25.34 mg), respectively. The orthogonal method was used for the extraction of phenolic compounds and extraction condition of each seaweed species was optimized. The antioxidant activity of extracted polyphenols from all three species stated that the polyphenols extracted from Undaria pinnatifida suringar demonstrated the highest antioxidative activity. Furthermore, gas chromatography–mass spectrometry (GC‐MS) was used for qualitative analysis of polyphenols, which revealed that the major components of polyphenols extracted from Undaria pinnatifida suringar were gallic acid and arbutin followed by syringate in Sargassum miyabei and phloretin in Sargassum thunbergii.

The antioxidant potential of different edible and medicinal mushrooms

Mushroom consumption has grown extraordinarily owing to their high nutritional value, desirable taste, and aroma. Mushrooms continue generating lots of interest chiefly in their consumption as food, as a cure for different ailments, as well as important goods for commerce throughout the globe owing to their dietary, antioxidant, and therapeutic values. Higher Ascomycetes and Basidiomycetes mushrooms have different properties with anticancer and immunological potential. They as well provide vital health benefits and display a wide-ranging continuum of pharmacological effects. The antioxidant activity of different mushrooms was reviewed for different radicals including DPPH, ABTS, OH, Nitrite, metals, and lipid peroxidation. The present review presents pharmacological activities of different species of edible and medicinal mushrooms. This review provides tangible evidence that these mushrooms are an excellent source of natural constituents and antioxidants with potential application in pharmaceuticals and in treating and managing different diseases.

The effect of onion and garlic on non-polar heterocyclic aromatic amines (α-, β-, γ- and δ-carbolines) formation in pan-fried meat and gravy

Thermal treatment of protein-rich food can lead to the formation of biologically active heterocyclic aromatic amines (HAAs). One of the methods to learn how to reduce the content as well as the influence of these compounds on heath is the study of factors inhibiting their synthesis. In the current investigation, the effect of onion and garlic on the formation of six possibly carcinogenic non-polar HAAs (α-, γ- and δ-carbolines) and two co-mutagenic β-carbolines (harmane and norharmane) was evaluated by comparing their contents in meat and gravy samples obtained from pan-fried pork dishes prepared in the presence and absence of these vegetables. Carbolines were isolated from food samples by solid phase extraction. The quantitative analysis was performed by high-performance liquid chromatography with fluorescence detection. The concentrations of individual compounds in dishes prepared without added vegetables ranged from 0.02 ng g^-1 (3-amino-1,4-dimethyl-5 H-pyrido(4,3-b)indole; Trp-P-1) to 10.1 ng g^-1 of meat (2-amino-9 H-pyrido[2,3-b]indole; AαC). Onion (30 g/100 g of meat) and garlic (15 g/100 g of meat) lowered the total content (in meat and gravy) of the α-, δ- and γ-carbolines in the range from 52% to 87%. In contrast, onion caused an increase in the norharmane concentration both in meat and gravy. The percentage of carbolines in the gravies (assuming that their total content in meat and gravy is 100%) was higher in dishes prepared with onion and garlic than in dishes without these seasonings.

Pseudosterins A-C, Three 1-Ethyl-3-formyl-β-carbolines from Pseudostellaria heterophylla and Their Cardioprotective Effects

Pseudostellaria heterophylla is used in China not only as a functional food but also as an herb to tonify the spleen, enhance immunity, and treat palpitation. Our previous investigation showed that a fraction enriched in glycosides obtained from the roots of P. heterophylla possessed pronounced protective effects on H9c2 cells against CoCl₂-induced hypoxic injury. However, the active compounds responsible for the observed effects were still unknown. In the current investigation, pseudosterins A–C (1–3), three new alkaloids with a 1-ethyl-3-formyl-β-carboline skeleton, together with polydatin, have been isolated from the active fraction. Their structures were elucidated on the basis of spectroscopic analysis and quantum chemical calculations. The four compounds showed cardioprotective effects against sodium hydrosulfite-induced hypoxia-reoxygenation injury in H9c2 cells, with the three alkaloids being more potent. This is also the first report of alkaloids with a β-carboline skeleton isolated from P. heterophylla as cardioprotective agents.

Occurrence, Formation from d-Fructose and 3-Deoxyglucosone, and Activity of the Carbohydrate-Derived β-Carbolines in Foods

β-Carbolines are naturally occurring bioactive alkaloids. In this work, carbohydrate-derived β-carbolines (βCs), 1-(1,3,4,5-tetrahydroxypent-1-yl)-β-carboline isomers (1a/b), 1-(1,4,5-trihydroxypent-1-yl)-β-carboline (2), 1-(1,5-dihydroxypent-3-en-1-yl)-β-carboline (3), and 1-(1,2,3,4,5-pentahydroxypent-1-yl)-β-carboline (4) were identified and analyzed in commercial foods. The concentrations of βCs 1-4 in foods ranged from undetectable to 11.4 μg/g levels, suggesting their intake in the diet. Processed foods contained higher amounts than fresh or unprocessed foods, and the highest content was found in processed tomato and fruit products, sauces, and baked foods. βCs 1-3 were formed in foods during heating, and 1a/b were the main compounds. The formation of carbohydrate-derived βCs was studied in model reactions of tryptophan and carbohydrates. They formed in reactions of tryptophan with glucose under acidic conditions at temperatures higher than 80 °C. The formation of 1a/b was favored, but 2-3 increased at high temperatures. Noticeably, the βCs 1-3 formed in the reactions of tryptophan with fructose or sucrose, and the formation from fructose was much higher than from glucose. Thus, fructose was the main carbohydrate involved in the formation of 1-3, whereas sucrose gave these βCs after acid hydrolysis. It is shown for the first time that the mechanism of formation of βCs 1-3 occurs from the sugar intermediate 3-deoxyglucosone that reacts with tryptophan affording these carbohydrate-derived βCs. A mechanism of reaction to give βCs 1-3 is proposed that relies on the tautomerism (keto-enediol or enamine-imine) of intermediates involved in the reaction. Carbohydrate βCs 1-4 were assessed as inhibitors of monoamine oxidase (MAO), as antioxidants, and for their interaction with DNA. They were not good inhibitors of MAO-A or -B, were poor antioxidants, and did not appreciably interact with DNA.

Identification of Compounds with Potential Therapeutic Uses from Sweet Pepper (Capsicum annuum L.) Fruits and Their Modulation by Nitric Oxide (NO)

Plant species are precursors of a wide variety of secondary metabolites that, besides being useful for themselves, can also be used by humans for their consumption and economic benefit. Pepper (Capsicum annuum L.) fruit is not only a common food and spice source, it also stands out for containing high amounts of antioxidants (such as vitamins C and A), polyphenols and capsaicinoids. Particular attention has been paid to capsaicin, whose anti-inflammatory, antiproliferative and analgesic activities have been reported in the literature. Due to the potential interest in pepper metabolites for human use, in this project, we carried out an investigation to identify new bioactive compounds of this crop. To achieve this, we applied a metabolomic approach, using an HPLC (high-performance liquid chromatography) separative technique coupled to metabolite identification by high resolution mass spectrometry (HRMS). After chromatographic analysis and data processing against metabolic databases, 12 differential bioactive compounds were identified in sweet pepper fruits, including quercetin and its derivatives, L-tryptophan, phytosphingosin, FAD, gingerglycolipid A, tetrahydropentoxylin, blumenol C glucoside, colnelenic acid and capsoside A. The abundance of these metabolites varied depending on the ripening stage of the fruits, either immature green or ripe red. We also studied the variation of these 12 metabolites upon treatment with exogenous nitric oxide (NO), a free radical gas involved in a good number of physiological processes in higher plants such as germination, growth, flowering, senescence, and fruit ripening, among others. Overall, it was found that the content of the analyzed metabolites depended on the ripening stage and on the presence of NO. The metabolic pattern followed by quercetin and its derivatives, as a consequence of the ripening stage and NO treatment, was also corroborated by transcriptomic analysis of genes involved in the synthesis of these compounds. This opens new research perspectives on the pepper fruit’s bioactive compounds with nutraceutical potentiality, where biotechnological strategies can be applied for optimizing the level of these beneficial compounds.

Enhancement of isoflavone aglycone, amino acid, and CLA contents in fermented soybean yogurts using different strains: Screening of antioxidant and digestive enzyme inhibition properties

This study was the first to evaluate changes in isoflavone, amino acid, conjugated linoleic acid (CLA), antioxidant effect, and digestive enzyme inhibition during fermentation of soy-milk to soy-yogurt with L. brevis and L. plantarum. Total average isoflavones were reduced (1318.2 → 971.1 μg/g) with an increase of aglycones (60.2 → 804.9 μg/g, genistein > daidzein > glycitein) in soy powder yogurts (SPYs). Amino acids increased considerably, as did ornithine (average 4.1 → 551.0 mg/g), and CLA showed high variations from not-detected (ND) to 0.5, 0.9 mg/g (cis-9, trans-11) and ND to 0.3, 0.2 mg/g (trans-10, cis-12). Digestive enzyme inhibitions (α-glucosidase, α-amylase, and pancreatic lipase) displayed high activities (average 50.6 → 67.2, 5.2 → 46.4, 10.6 → 51.4%). Moreover, the antioxidant abilities against radicals were elevated as follows: ABTS > DPPH > hydroxyl (average 63.5 → 86.5, 50.2 → 70.3, 39.3 → 55.2%). Specifically, SPY using mixed strains exhibited the greatest enzymatic inhibition and antioxidant capacities.

Downstream Signalling from Molecular Hydrogen

Molecular hydrogen (H2) is now considered part of the suite of small molecules that can control cellular activity. As such, H2 has been suggested to be used in the therapy of diseases in humans and in plant science to enhance the growth and productivity of plants. Treatments of plants may involve the creation of hydrogen-rich water (HRW), which can then be applied to the foliage or roots systems of the plants. However, the molecular action of H2 remains elusive. It has been suggested that the presence of H2 may act as an antioxidant or on the antioxidant capacity of cells, perhaps through the scavenging of hydroxyl radicals. H2 may act through influencing heme oxygenase activity or through the interaction with reactive nitrogen species. However, controversy exists around all the mechanisms suggested. Here, the downstream mechanisms in which H2 may be involved are critically reviewed, with a particular emphasis on the H2 mitigation of stress responses. Hopefully, this review will provide insight that may inform future research in this area.

A review on β-carboline alkaloids and their distribution in foodstuffs: A class of potential functional components or not?

Pharmacologically active β-carboline alkaloids (βCs) such as harman, norharman and some others are naturally present in plants and occur in many foodstuffs. They have a lot of pharmacological properties, including antitumor, antioxidant, anti-inflammatory and antimicrobial effects, and possess the potential for treating Alzheimer's disease, Parkinson's disease, depression and other central nervous system diseases. Dietary intake is proven to be an important source of βCs. Therefore, it is important to know the amounts of βCs that can be gotten from daily diets. This review summarizes the pharmacological activities, toxicology and formation of βCs, and gives collective information on contents of βCs in different foodstuffs.

Potential of natural products as radioprotectors and radiosensitizers: opportunities and challenges

Natural products can be used as natural radiosensitizers and radioprotectors, showing promising effects in cancer treatments in combination with radiotherapy, while reducing ionizing radiation (IR) damage to normal cells/tissues. The different effects of natural products on irradiated normal and tumor cells/tissues have attracted more and more researchers' interest. Nonetheless, the clinical applications of natural products in radiotherapy are few, which may be related to their low bioavailability in the human body. Here, we displayed the radiation protection and radiation sensitization of major natural products, highlighted the related molecular mechanisms of these bioactive substances combined with radiotherapy to treat cancer, and critically reviewed their deficiency and improved measures. Lastly, several clinical trials were presented to verify the clinical application of natural products as radiosensitizers and radioprotectors. Further clinical evaluation is still needed. This review provides a reference for the utilization of natural products as radiosensitizers and radioprotectors.

2',7'-dichlorofluorescin-based analysis of Fenton chemistry reveals auto-amplification of probe fluorescence and albumin as catalyst for the detection of hydrogen peroxide

Fluorophore 2',7'-dichlorofluorescin (DCF) is the most frequently used probe for measuring oxidative stress in cells, but many aspects of DCF remain to be revealed. Here, DCF was used to study the Fenton reaction in detail, which confirmed that in a cell-free system, the hydroxyl radical was easily measured by DCF, accompanied by the consumption of H2O2 and the conversion of ferrous iron into ferric iron. DCF fluorescence was more specific for hydroxyl radicals than the measurement of thiobarbituric acid (TBA)-reactive 2-deoxy-D-ribose degradation products, which also detected H2O2. As expected, hydroxyl radical-induced DCF fluorescence was inhibited by iron chelation, anti-oxidants, and hydroxyl radical scavengers and enhanced by low concentrations of ascorbate. Remarkably, due to DCF fluorescence auto-amplification, Fenton reaction-induced DCF fluorescence steadily increased in time even when all ferrous iron was oxidized. Surprisingly, the addition of bovine serum albumin rendered DCF sensitive to H2O2 as well. Within cells, DCF appeared not to react directly with H2O2 but indirect via the formation of hydroxyl radicals, since H2O2-induced cellular DCF fluorescence was fully abolished by iron chelation and hydroxyl radical scavenging. Iron chelation in H2O2-stimulated cells in which DCF fluorescence was already increasing did not abrogate further increases in fluorescence, suggesting DCF fluorescence auto-amplification in cells. Collectively, these data demonstrate that DCF is a very useful probe to detect hydroxyl radicals and hydrogen peroxide and to study Fenton chemistry, both in test tubes as well as in intact cells, and that fluorescence auto-amplification is an intrinsic property of DCF.

Antioxidative activity of oyster protein hydrolysates Maillard reaction products

A two-step process of enzymatic hydrolyzation followed by Maillard reaction was used to produce oyster meat hydrolysate Maillard reaction products (MRPs). The flavor of oyster meat hydrolysate MRPs was significantly improved through an optimized orthogonal experimental design. Comparisons between the antioxidative activities of oyster meat hydrolysates and their MRPs were made using lipid peroxidation inhabitation, hydroxyl radical scavenging radical activity, and radical scavenging activity of 2,2 diphenyl-1-picrylhydrazyl (DPPH). These methods indicated that an improvement of Maillard reaction on the oyster meat hydrolysates antioxidative activity. Gas chromatography-mass spectrometry illustrated that the increase was due to the newly formed antioxidative compounds after Maillard reaction, mainly of acids from 22.45% to 37.77% and phenols from 0% to 9.88%.

Detection of Hydroxyl Radicals Using Cerium Oxide/Graphene Oxide Composite on Prussian Blue

A composite sensor consisting of two separate inorganic layers of Prussian blue (PB) and a composite of cerium oxide nanoparticles (CeNPs) and graphene oxide (GO), is tested with •OH radicals. The signals from the interaction between the composite layers and •OH radicals are characterized using cyclic voltammetry (CV). The degradation of PB in the presence of H₂O₂ and •OH radicals is observed and its impact on the sensor efficiency is investigated. The results show that the composite sensor differentiates between the solutions with and without •OH radicals by the increase of electrochemical redox current in the presence of •OH radicals. The redox response shows a linear relation with the concentration of •OH radicals where the limit of detection, LOD, is found at 60 µM (100 µM without the PB layer). When additional composite layers are applied on the composite sensor to prevent the degradation of PB layer, the PB layer is still observed to be degraded. Furthermore, the sensor conductivity is found to decrease with the additional layers of composite. Although the CeNP/GO/PB composite sensor demonstrates high sensitivity with •OH radicals at low concentrations, it can only be used once due to the degradation of PB.

Harmine Acts as an Indirect Inhibitor of Intracellular Protein Aggregation

Protein aggregation and oxidative stress are two pathological hallmarks of a number of protein misfolding diseases, including Huntington's disease (HD). Whether protein aggregation precedes elevation of oxidative stress or follows it remains ambiguous. We have investigated the role of harmine, a beta-carboline alkaloid, in aggregation of a mutant huntingtin fragment (103Q-htt) in a yeast model of HD. We observed that harmine was able to decrease intracellular aggregation of 103Q-htt, and this reduction was higher than that observed with trehalose, a conventional protein stabilizer. The presence of harmine also decreased prion formation. Decreased protein aggregation was accompanied by reduction in oxidative stress. However, harmine had no effect on aggregation of the mutant huntingtin fragment in vitro. Thus, based on experimental data, we conclude that the antioxidant harmine lowers aggregation-induced elevation in oxidative stress, which slows down intracellular protein aggregation.

Comparative analysis of isoflavone aglycones using microwave-assisted acid hydrolysis from soybean organs at different growth times and screening for their digestive enzyme inhibition and antioxidant properties

The objectives of this research were to demonstrate the changes in isoflavone-aglycones, total phenolics, and biological properties (digestive enzyme inhibition; antioxidant) from six organs including leaves, leafstalks, roots, stems, seeds, and pods at different growth times of soybean plant. Three isoflavone-aglycones in microwave-assisted acid hydrolysis extracts were elucidated using UHPLC-ESI-Q-TOF-MS/MS and their contents exhibited remarkable differences in leaves (245.93-2239.33 μg/g), roots (854.96-4425.34 μg/g), and seeds (ND-2339.62 μg/g). Specifically, the collected samples on 15-Oct (leaves: 2239.33; seeds: 2339.62 μg/g) and 31-Aug (roots: 4425.34 μg/g) showed the highest isoflavone-aglycones, and daidzein was observed the most abundant component, comprising approximately 70%. Moreover, the inhibitions against α-glucosidase and α-amylase displayed the predominant effects in roots (89;91%) and leaves (81;85%) of samples on 31-Aug and 15-Oct at 300 μg/ml. The antioxidant activities on ABTS, DPPH, and hydroxyl radicals increased considerably with the increases of growth times in leaves and seeds, especially, ABTS showed the highest scavenging abilities: leaves (15-Oct;83%) > roots (31-Aug;75%) > seeds (15-Oct;68%). Therefore, our results suggest that soybean leaves, roots and seeds may be considered as excellent natural sources for nutraceuticals.

Quantitative Structure-Activity Relationship Model to Predict Antioxidant Effects of the Peptide Fraction Extracted from a Co-Culture System of Chlorella pyrenoidosa and Yarrowia lipolytica

In this study, the antioxidant components in co-culture of Chlorella pyrenoidosa and Yarrowia lipolytica (3:1 ratio) were confirmed as trypsin-hydrolyzed peptides (EHPs). The EHPs were composed of 836 different peptides with molecular weights ranging from 639 to 3531 Da and were mainly composed of hydrophobic amino acids (48.1%). These peptides showed remarkable protective effects against oxidative stress in HepG2, which may be attributed to their structures. Furthermore, the mRNA and protein levels of nuclear factor erythroid 2-related factor 2 (Nrf2) were significantly lower in the peptide-treated group than in the control group, suggesting that the antioxidant enzyme-coding genes were not activated. The EC50 value of three peptides in the EHPs were in the order of AGYSPIGFVR (0.04 ± 0.002 mg/mL) > VLDELTLAR (0.09 ± 0.001 mg/mL) > LFDPVYLFDQG (0.41 ± 0.03 mg/mL); these results agreed with the prediction of the model (R2 > 0.9, Q2 > 0.5). Thus, EHPs show potential as potent new antioxidant agents.

β-carboline alkaloids attenuate bleomycin induced pulmonary fibrosis in mice through inhibiting NF-kb/p65 phosphorylation and epithelial-mesenchymal transition

ETHNOPHARMACOLOGICAL RELEVANCE

The plant Arenaria kansuensis is used in traditional medicine to treat lung inflammation for a long time. However, the anti-pulmonary fibrosis effect and its corresponding bioactive constituents of this plant have not been studied extensively.

AIM OF THE STUDY

The purpose of this study was to investigate the anti-pulmonary fibrosis effect and its corresponding bioactive constituents of A. kansuensis and its possible mechanism.

MATERIALS AND METHODS

In vivo experiment, the anti-pulmonary fibrosis effects of the fraction (Part1) enriched from ethyl acetate extracts of the whole plant A. kansuensis were evaluated through bleomycin (BLM)-induced pulmonary fibrosis mice (five groups, n = 10) daily at doses of 50, 100 and 150 mg/kg for 15 days. In vitro experiment, the anti-inflammation and reversed epithelial-mesenchymal transition (EMT) effect of 12 β-carboline alkaloids isolated from Part1 were evaluated through lipopolysaccharide (LPS)-induced RAW264.7 inflammatory cell model and TGF-β1 induced A549 cell model.

RESULTS

In this study, a fraction named Part1 extracted from Arenaria kansuensis presented strong anti-pulmonary fibrosis effect at the dose of 150 mg/kg. Vivo experiments showed that the survival rate and body weight of mice significantly increased after Part1 treatment. Part1 could significantly inhibit the initial of inflammation, deposition of collagen and expression of TGF-β1 and α-SMA, moreover, the expression of E-cadherin was significantly elevated after administration of Part1. All the cure effects of Part1 were in dose dependent manner. A total of 12 β-carboline alkaloids were identified in Part1 and they all showed suppressive effect on inflammatory cytokines including MCP-1, TNF-α, IL-6 and IL-1β through inhibition of NF-kb/p65 phosphorylation, and that epithelial-mesenchymal transition (EMT) process was reversed by different compounds in different levels. The expression of indicators of EMT including α-SMA, vimentin and E-cadherin was significantly improved after given different β-carboline alkaloids.

CONCLUSIONS

This study showed that antifibrogenic effect of β-carboline alkaloids was due to inhibiting the initial of inflammation through NF-kb/p65 pathway and reversing the process of EMT.

The Human Fecal Microbiota Metabolizes Foodborne Heterocyclic Aromatic Amines by Reuterin Conjugation and Further Transformations

SCOPE

Heterocyclic aromatic amines (HAAs) are process-induced food contaminants with high mutagenic and/or carcinogenic potential. Although the human gut microbiota is known to affect the metabolism of dietary constituents, its impact on HAA metabolism and toxicity has been little studied. Here, the glycerol-dependent metabolism of seven foodborne HAAs (AαC, Trp-P-1, harman, norharman, PhIP, MeIQx, and MeIQ) by the human fecal microbiota is investigated.

METHODS AND RESULTS

As analyzed by HPLC-DAD/FLD, the extent of conversion is strongly dependent on glycerol supplementation and HAA structure. AαC (60-100%) and the 2-aminoimidazoazarenes (up to 58%) are especially prone to microbial conversion. Based on high-resolution MS and/or NMR spectroscopy data, 70 fecal metabolites are identified in total, mainly formed by chemical reactions with one or two molecules of microbially derived reuterin. Moreover, it has been demonstrated that the human fecal microbiota can further transform reuterin adducts by reduction and/or hydroxylation reactions. Upon isolation, some reuterin-induced HAA metabolites appear to be partially unstable, complicating structural identification.

CONCLUSION

The formation of microbial metabolites needs to be incorporated into risk assessment considerations for HAAs in human health. In this study, several HAA metabolites, mainly reuterin-dependent, are identified in vitro, providing the basis for future human studies investigating microbial HAA metabolism.

Estimation of phytochemical constituents and in vitro antioxidant potencies of Brachychiton populneus (Schott & Endl.) R.Br

Background

Plants either in raw form or their isolated bioactive constituents are utilized as complementary and alternative medicine in various disorders. The present study was designed to evaluate chief phytochemical constituents of various fractions of Brachychiton populneus leaves and its antioxidative aptitude against free radicals.

Methods

Various fractions of B. populneus were prepared through solvent–solvent extraction technique based on their polarity and screened for phytochemical classes, total phenolic (TPC), flavonoid (TFC) and total tannin (TTC) content. Antioxidant effects of the extracts were manifested by in vitro multidimensional assays i.e. DPPH, hydroxyl radical scavenging, iron chelating, nitric oxide scavenging, β-carotene bleaching, phosphomolybdenum and reducing power assay.

Results

Qualitative screening of various fractions of B. populneus ensured the presence of alkaloids, saponins, terpenoids, phenols, tannins, triterpenoids and flavonoids. Quantitative analysis revealed that aqueous fraction (BPA) showed maximum quantity of TPC and TFC followed by BPE and BPB. In terms of IC₅₀ values BPA exhibited minimum values in all the in vitro antioxidant assays. However, the phytochemicals and yield did not accumulate in various fractions on polarity.

Conclusion

Our results indicated the presence of various polyphenolics, flavonoids, alkaloids etc. The yield of various fractions and qualitative phytochemical analysis did not correlate with polarity of solvents. Various antioxidant assays exhibited significant (p < 0.05) correlation with TPC and TFC and renders B. populneus with therapeutic potential against free-radical-associated oxidative damages and this effect was significant with BPA.

Electronic supplementary material

The online version of this article (10.1186/s13065-019-0549-z) contains supplementary material, which is available to authorized users.

Comparisons of nutritional constituents in soybeans during solid state fermentation times and screening for their glucosidase enzymes and antioxidant properties

This research was the first to demonstrate the variations of nutritional constituents, glucosidase properties and antioxidant activities in soybeans during different solid state fermentation times (germination → 5 periods for 12 days) with Tricholoma matsutake. Total isoflavones were significantly reduced (2661.54 → 1559.04 μg/g) with the increase of aglycone contents (107.61 → 1285.66 μg/g, 12 times) for fermentation, whereas amino acid and fatty acid slightly increased. Among them, daidzein (43.2 → 43.6 → 421.9 → 721.4 → 634.0 μg/g), genistein (52.7 → 24.4 → 339.5 → 546.6 → 512.8 μg/g) and glutamic acid (0.3 → 1.7 → 3.9 → 6.6 → 16.1 mg/g) markedly increased between germinated and fermented soybeans. Total phenolic contents and antioxidant abilities also considerably increased, especially, ABTS displayed the predominant scavenging capacities (33.1 → 94.8%) at 200 μg/ml, followed by DPPH (11.9 → 87.0%) and hydroxyl (11.2 → 49.2%) radicals. Interestingly, α-glucosidase inhibition (11.8 → 84.9%) and β-glucosidase (3.1 → 40.3 unit/g) exhibited the highest activities after 9 days. Our results implied that fermented soybeans may be contributed to enhance the soybean value in nutrition and biological effect aspects to development of new functional foods.

Bioactivity of selected materials for coffee substitute

Epidemiological studies have suggested that coffee consumption is negatively correlated with the incidence of Parkinson's disease. Coffee contains relatively high levels of β-carbolines, which have been ascribed neuroactive effects in humans however the positive or negative effect has not been confirmed yet. Two ingredients with applications as coffee substitutes-chicory, which is traditionally used in this way, and artichoke-were considered in this study both from the neuroactive point of view but also in relation to the other bioactive compounds that result from their thermal processing. These thermal products are of concern because of their possible toxic properties. The estimated concentration of β-carbolines was high in both materials (1.8 μg/g and 2.5 μg/g harman and 2.9 μg/g and 3.1 μg/g norharman in chicory and artichoke, respectively). Artichoke had more β-carbolines than chicory, and also more all the toxic compounds examined here-acrylamide, carboxymethyllysine, and furans, which were detected in significantly higher concentrations in artichoke, particularly acrylamide. Chicory and artichoke also contain phenolic compounds that possess high antioxidant activity, on a similar level. Artichoke, a new proposed ingredient in coffee substitutes, appears to be a richer source of β-carbolines than the traditionally chicory. Both materials contained high level of undesirable components, such as furan and its derivatives, carboxymethyllysine and particularly acrylamide, much higher in artichoke.

Guanosine Protects Striatal Slices Against 6-OHDA-Induced Oxidative Damage, Mitochondrial Dysfunction, and ATP Depletion

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by loss of dopaminergic neurons in substantia nigra pars compacta which induces severe motor symptoms. 6-OHDA is a neurotoxin widely used in PD animal models due to its high affinity by dopamine transporter, its rapid non-enzymatic auto-oxidation which generates reactive oxygen species (ROS), oxidative stress, and for induced mitochondrial dysfunction. We previously reported an in vitro protocol of 6-OHDA-induced toxicity in brain regions slices, as a simple and sensitive assay to screen for protective compounds related to PD. Guanosine (GUO), a guanine-based purine nucleoside, is a neuroprotective molecule that is showing promising effects as an antiparkinsonian agent. To investigate the mechanisms involved on GUO-induced neuroprotection, slices of cortex, striatum, and hippocampus were incubated with GUO in the presence of 6-OHDA (100 μM). 6-OHDA promoted a decrease in cellular viability and increased ROS generation in all brain regions. Disruption of mitochondrial potential, depletion in intracellular ATP levels, and increase in cell membrane permeabilization were evidenced in striatal slices. GUO prevented the increase in ROS generation, disruption in mitochondrial potential, and depletion of intracellular ATP induced by 6-OHDA in striatal slices. In conclusion, GUO was effective to prevent oxidative events before cell damage, such as mitochondrial disruption, intracellular ATP levels depletion, and ROS generation in striatal slices subjected to in vitro 6-OHDA-induced toxicity.

Antioxidative Potential of a Streptomyces sp. MUM292 Isolated from Mangrove Soil

Mangrove derived microorganisms constitute a rich bioresource for bioprospecting of bioactive natural products. This study explored the antioxidant potentials of Streptomyces bacteria derived from mangrove soil. Based on 16S rRNA phylogenetic analysis, strain MUM292 was identified as the genus Streptomyces. Strain MUM292 showed the highest 16S rRNA gene sequence similarity of 99.54% with S. griseoruber NBRC12873^T. Furthermore, strain MUM292 was also characterized and showed phenotypic characteristics consistent with Streptomyces bacteria. Fermentation and extraction were performed to obtain the MUM292 extract containing the secondary metabolites of strain MUM292. The extract displayed promising antioxidant activities, including DPPH, ABTS, and superoxide radical scavenging and also metal-chelating activities. The process of lipid peroxidation in lipid-rich product was also retarded by MUM292 extract and resulted in reduced MDA production. The potential bioactive constituents of MUM292 extract were investigated using GC-MS and preliminary detection showed the presence of pyrazine, pyrrole, cyclic dipeptides, and phenolic compound in MUM292 extract. This work demonstrates that Streptomyces MUM292 can be a potential antioxidant resource for food and pharmaceutical industries.

New 2-Aryl-9-methyl-β-carbolinium salts as Potential Acetylcholinesterase Inhibitor agents: Synthesis, Bioactivity and Structure-Activity Relationship

A series of 2-aryl-9-methyl-β-carbolinium bromides (B) were synthesized and explored for anti-acetylcholinesterase (AChE) activities in vitro, action mechanism and structure-activity relationship. All the compounds B along with their respective 3,4-dihydro intermediates (A) presented anti-AChE activity at 10 μM. Thirteen compounds B showed the excellent activity with IC₅₀ values of 0.11–0.76 μM and high selectivity toward AChE relative to butyrylcholinesterase (BChE), superior to galantamine (IC₅₀ = 0.79 μM), a selective AChE inhibitor drug. Kinetic analysis showed that the action mechanisms of both compounds B and A are a competitive inhibition model. Structure-activity relationship analyses showed that the C = N⁺ moiety is a determinant for the activity. Substituents at 6, 7 or 4′ site, the indole-N-alkyl and the aromatization of the C-ring can significantly improve the activity. Molecular docking studies showed that the compounds could combine with the active site of AChE by the π-π or cation-π action between the carboline ring and the phenyl rings of the residues, and the β-carboline moiety is embedded in a cavity surrounded by four aromatic residues of Trp86, Tyr337, Trp439 and Tyr449. The present results strongly suggest that the para-position of the D-ring should be a preferred modification site for further structural optimization design. Thus, 2-aryl-9-methyl-β-carboliniums emerged as novel and promising tool compounds for the development of new AChE inhibitor agents.

Improvement of nutritional components and in vitro antioxidative properties of soy-powder yogurts using Lactobacillus plantarum

This research was the first to demonstrate changes in nutritional compositions (isoflavone and CLA) from the 50% methanol extracts of soy-powder milk (SPM) and soy-powder yogurt (SPY) through fermentation using Lactobacillus plantarum S48 and P1201 strains. The radical scavenging activities and protective effects against oxidative stress in LLC-PK₁ cells were also investigated. The average physicochemical characteristics including acidity and viable cell number as well as β-glucosidase activity increased with 0.2 → 0.7%, 7.5 → 9.8 log cfu/mL, and 0.0 3 → 1.75 U/g in SPYs. Total average isoflavones were considerably reduced (3180.3 → 2018.3 μg/g) with the increase of aglycone contents (191.8 → 770.2 μg/g), especially, daidzein exhibited the most remarkable increase rate (98.6 → 460.9 μg/g; > 4.8 times) during fermentation. The CLA and total phenolics also increased with significant differences (ND → 1.6 mg/g; 2.4 → 3.6 mg/GAE/g) between SPM and SPY. Interestingly, the cis-9, trans-11 CLA showed approximately 90% in total content. Moreover, the scavenging capacities against three radicals markedly increased with about 30% in SPYs, as the following order: ABTS > hydroxyl > DPPH. The protective effects on oxidative stress (py-rogallol: O2-, SNP: NO, and SIN-1: ONOO⁻) were also observed high cell viabilities (>10%) under LLC-PK₁ cellular system. Our results suggest that SPY may be utilized as a potent source regarding natural antioxidants and beneficial components for health food and medical uses.

Nitrosative deamination of 2'-deoxyguanosine and DNA by nitrite, and antinitrosating activity of β-carboline alkaloids and antioxidants

Endogenous and dietary nitrite produces reactive nitrogen species (RNS) that react with DNA causing mutations. The nitrosation of 2'-deoxyguanosine (dGuo) and DNA with nitrite was studied under different conditions, and the reaction and degradation products identified and analysed by HPLC-DAD-MS. Nitrosative deamination of dGuo produced xanthine along with 2'-deoxyxanthosine whereas DNA afforded xanthine. Formation of xanthine increased with nitrite concentration and in low pH such as that of stomach. Xanthine was measured as a marker of nitrosation of dGuo and DNA, and it was subsequently used to study the antinitrosating activity of β-carboline alkaloids, and selected antioxidants. Food-occurring tetrahydro-β-carbolines (THβCs) decreased nitrosative deamination of dGuo and DNA under conditions simulating the stomach. Antinitrosating activity was also evidenced for flavonoids (catechin, quercetin) and indole (melatonin) antioxidants. Among THβCs the most active antinitrosating compounds were 1,2,3,4-tetrahydro-β-carboline-3-carboxylic acids (THβC-3-COOHs) that reacted with nitrite to give N-nitroso derivatives as main products along with 3,4-dihydro-β-carboline-3-carboxylic acids and aromatic β-carbolines (norharman and harman). Antinitrosating activity of THβCs correlated well with the formation of N-nitroso-THβC-3-COOHs. These N-nitroso derivatives were stable at pH 7 but degraded in acid conditions affording nitrosating species.

Melatonin as a versatile molecule to design novel multitarget hybrids against neurodegeneration

Melatonin is an indoleamine produced mainly in the pineal gland. The natural decline of melatonin levels with aging strongly contributes to the development of neurodegenerative disorders. Pleiotropic actions displayed by melatonin prevent several processes involved in neurodegeneration such as neuroinflammation, oxidative stress, excitotoxicity and/or apoptosis. This review focuses on a number of melatonin hybrids resulting from the juxtaposition of tacrine, berberine, tamoxifen, curcumin, N,N-dibenzyl(N-methyl)amine, among others, with potential therapeutic effects for the treatment of neurodegenerative diseases.